1. Field of the Invention
The present invention relates to an image printing apparatus for, after printing an image on printing paper on the basis of an image signal, cutting the paper to obtain cut printing paper.
2. Background of the Invention
FIG. 16 roughly shows a structure of a printing unit (hereinafter referred to as a printing mechanical unit) 12 of the image printing apparatus using a thermal transfer recording method with a roll type of printing paper.
In FIG. 16, a thermal head 1 for patterning an image signal to thermally transfer it to printing paper is in contact with an ink sheet 2 coated by a thermal-soluble or thermal-sublimation ink for thermal transfer recording. Under the ink sheet 2 provided is printing paper 3. The ink sheet 2 and the printing paper 3 are brought into intimate contact with the thermal head 1 by being pressed by a platen roller 4 opposed to the thermal head 1, so that an image pattern in the thermal head 1 is thermally transferred to the printing paper 3 via the ink sheet 2. After the thermal transfer, the ink sheet 2 and the printing paper 3 are sent out by the rotation of the platen roller 4.
The ink sheet 2 and the printing paper are long roll types of paper. The ink sheet 2 is supplied from an ink sheet supply roll 201, and rolled up by an ink sheet take-up roll 202. The printing paper 3 is supplied from a printing paper supply roll 301, sent in a discharge direction via the proton roller 4 by a pinch roller 5, and cut by a cutter 6 on the basis of a cutting command from a CPU 10.
Next, a structure of an image printing apparatus 90 will be described with reference to FIG. 17. The image printing apparatus 90 is an apparatus for making a print by receiving an image signal inputted from the outside. It has an input terminal T1 for inputting a digital image signal.
The input terminal T1 is directly connected to a memory controller 22 which is an input and output interface of an image or control signal.
The memory controller 22 is connected to a frame memory 21 for storing picture information of one frame, a CPU (central processing unit) 10, and a transfer circuit 23 for making a data conversion for printing. The transfer circuit 23 is connected to the thermal head 1 of the printing mechanical unit 12.
The CPU 10 reads or writes an image signal from and to the frame memory 21 via the memory controller 22, and also has a function for controlling the printing mechanical unit 12 via a mechanical controller 11 which will be described later.
Further, the CPU 10 is connected to the mechanical controller 11 for controlling the mechanism of the printing mechanical unit 12, and the mechanical controller 11 is connected to all the equipment described with reference to FIG. 16. The CPU 10 is also connected to a programmable ROM 13 for storing, for example, a predetermined cutting position of the printing paper.
In such a structure, the digital image signal inputted via the input terminal T1 is temporarily stored into the frame memory 21 via the memory controller 22 under the control of the CPU 10.
The image signal stored in the frame memory 21 is read by the transfer circuit 23 via the memory controller 22 under the control of the CPU 10. The transfer circuit 23 converts the image signal into data for printing, and send it to the thermal head 1 of the printing mechanical unit 12. The data conversion of the image signal into the data for printing by the transfer circuit 23 includes a color conversion from an RGB signal to a YMC (yellow, magenta, and cyanogen) signal, a conversion from a YMC signal to a pulse signal for operating the thermal head, or the like.
Then, the thermal head 1 heats a heater line (an array of heating elements disposed on the head) for a given time to sink a thermal-soluble or thermal-sublimation ink applied to the ink sheet 2 into the printing paper 3 by means of thermal solution or thermal sublimation, thereby printing an image on the printing paper 3 on the basis of the data for printing obtained from the transfer circuit 23.
The printed printing paper is sent out by the pinch roller 5 of the printing mechanical unit 12, and cut by the cutter 6 on the basis of the cutting command from the CPU 10. A cutting position of the printed printing paper has been preset and stored in the programmable ROM 13. Thus, the CPU 10 gives the cutting command which indicates the cutting position stored in the programmable ROM 13 to the cutter 6 of the printing mechanical unit 12 via the mechanical controller 11. In order to change the cutting position, the programmable ROM 13 needs to be rewritten.
According to the structure of the printing mechanical unit 12 as shown in FIG. 16, the printing paper 3 has a blank area of a length L1 from the heater line of the thermal head 1 to the pinch roller 5. FIG. 18 shows an example of cut printing paper 30 outputted from the image printing apparatus 90. As shown in the figure, an area of the length L1 from the top end of the cut printing paper 30 to a printing start position RS is blank. This blank area is a margin M1 which is so wide that one can hold it.
In the conventional image printing apparatus 90, the printing paper is cut only one time after printing to a predetermined size at a cutting position CP in the vicinity of a printing end position RE, so that the wide margin M1 remains on the cut printing paper 30. If the cutting position CP is shifted to the opposite direction to a discharge direction of the paper, a margin M2 corresponding to a shift length L2 of the cutting position CP remains.
Since a width W1 of a heater line 16, which is a print width of the thermal head 1, is smaller than a width W2 of the printing paper 3 as shown in FIG. 19, a margin M3 of a length 13 and M4 of a length L4 also remain at the left and right of the printing paper 30, respectively, after printing.
Likewise, even for a multiple printing where a plurality of printing images are longitudinally printed in one print area as is the case with cut printing paper 31 in FIG. 20, the margins M1 to M4 remain even after the area is divided into printing images 311.
As described above, the conventional image printing apparatus 90 leaves the margins M1 to M4 at the top and bottom or the left and right of the cut printing paper 30. Especially at the printing start position RS, the wide margin M1 remains.